Over the last 30 years, there has been a significant rise in the number of women participating in exercise. However, research on female athletes and those interested in general fitness has not kept pace with this exponential rise in participation.
One area of research on women that has been neglected is the effects of the menstrual cycle on exercise performance, more specifically, how menstruation might affect strength, aerobic and anaerobic capabilities, and muscle recovery.
Menstrual Cycle And Exercise Key Points:
The menstrual cycle is a biological process that supports reproduction.
The three main phases of the cycle are the follicular, ovulatory, and luteal phases.
During each phase, the fluctuations of two primary sex hormones, estrogen and progesterone, might impact exercise performance in women.
However, any detrimental effects of menstruation on exercise are trivial at best during the different phases.
Instead, it is recommended that women track their cycles and training and combine them to develop an individualized approach to exercise and nutrition.
Before we discuss how the menstrual cycle might affect exercise performance, we first need to understand:
Let’s dive in!
You can think of the menstrual cycle as an essential biological process where there are significant changes in a woman’s sex hormones. The primary purpose of these fluctuations is to support reproduction, BUT they also might exert various effects on the cardiovascular, respiratory, metabolic, and neuromuscular systems. These effects might affect exercise performance.
The menstrual cycle can be divided into six separate phases. In order, these are:
Next, let’s discuss the two primary hormones found in each phase and how their levels fluctuate.
The two key hormones that fluctuate during the menstrual cycle are estrogen and progesterone. Let’s briefly discuss each before moving on to how they rise and fall during each menstruation phase.
Estrogen plays various roles in the body, but one of its primary functions is it helps develop and maintain both the reproductive system and female characteristics. Furthermore, estrogen can be broken down into three different types.
It’s also important to know that estrogen is a very anabolic (muscle building) hormone and may help increase glycogen storage while increasing fat utilization. All of which could have important implications for exercise performance.
Next, let’s discuss estrogens counterpart, progesterone.
Progesterone is the other primary hormone involved in the menstrual cycle. Its purpose is to prevent the fertilization of more than one egg and strengthen the pelvic muscle walls in preparation for labor.
Progesterone can also be thought of as the ying to estrogens yang. Meaning as progesterone levels rise during menstruation, estrogen levels fall.
This is important to remember as we move on to the next section of this article. How this rise and fall of estrogen and progesterone during each phase of the menstrual cycle might positively or negatively affect exercise.
During this phase, concentrations of both estrogen and progesterone are low.
As we mentioned earlier, estrogen is a potent anabolic hormone that helps protect against exercise-induced muscle damage while also reducing inflammatory responses. When levels are low, there is a possibility of adverse effects on muscular performance or maximal and submaximal intensity exercise performance.
On the flip side, during the follicular phase (and due to low estrogen), the body might be able to utilize more glucose/glycogen. This can be highly advantageous for exercise, especially for longer duration/higher intensity training and events. It can also benefit those who strength train as working muscles use creatine phosphate and muscle glycogen as primary fuel sources.
In sum, even though muscle performance and performance might be slightly reduced during the early follicular phase due to low estrogen, the increased utilization of glycogen by the body might help offset it.
Estrogen concentrations (anabolic hormone) rise during the late follicular phase while progesterone levels remain low. Compared to the early follicular phase, this may be ideal for focusing on strength training where the environment is primed.
High weight (75-85% of 1 repetition max), medium reps, and medium rest periods should be emphasized during this period. This may lead to more significant gains in strength and quicker recovery times when combined with the higher estrogen levels.
For example, one could perform four sets of 8 reps of compound exercises (bench press, deadlift, shoulder press, squat) with 75 seconds of rest between sets and 2 minutes of rest between exercises.
Cardio-wise, high-intensity interval training would be ideal for improving cardiorespiratory fitness during the late follicular phase.
However, it must be stressed that more research is needed to verify this theory.
Estrogen will continue to rise (progesterone remains low) and hit its highest level during this phase. This has the potential to impact substrate metabolism. More specifically, your body can store and use carbohydrates as energy.
Carbohydrates act as the primary fuel source when exercise intensity increases and moves from more aerobic to anaerobic. Anaerobic metabolism (think strength training, intervals, or HIIT) can only be fueled by carbohydrates. Without carbs, high-intensity exercise cannot be maintained.
During this phase, it is recommended to keep the intensity low as your body utilizes more fat as an energy source during exercise.
During the luteal phase, both estrogen and progesterone levels are high. A 2019 study suggests that bloating and fatigue are common symptoms that can make exercise feel uncomfortable during this phase.
Heart rate and core body temperature may also increase during the luteal phase, hurting performance when exercising in the heat and humidity.
Lastly, central nervous system fatigue is high in this phase, and the increased progesterone levels can contribute to sodium loss.
With all the above considered, it is best to stick to low-intensity exercise during this phase while also avoiding exercise in hot conditions.
From the available research, knowing menstruation’s effects (positive and negative) on exercise might help a woman develop a training program where certain performance variables are focused on during each phase.
In addition to the above information, it is also recommended that women track their cycles and training and combine them to develop an individualized approach to exercise and nutrition. Reach out to our health coaching team for help developing a personalized strategy.